Automatic telephone exchange



April 1 1924.

F. A. LUNDQUIST AUTOMATIC TELEPHONE EXCHANGE Filed Oct. 12 1917 entree stares PATENT orrlcs.

FRANK A. LUNDQUIS'I, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO HENRY S. CONRAD, TRUSTEE.

AUTOM'A'IIC TELEPHONE EXCHANGE.

Application filed October 12, 1917. Serial No. 196,124.

To all 107mm it may concern:

Be it known that I, FRANK A. LUND UIs'r, a citizen of the United States of America, and a resident of the city of Chicago, county of (look, and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Exchanges, of which the following is a specification.

My invention relates to automatic telephone exchanges, and has for its object improvements in such exchanges.

In automatic telephone exchanges, each subscriber has a line switch in the central oifice and connected to the line which runs to the subscribers sub-station. At the line switch, and bridged across the line, are two line relays. When a subscriber removes his receiver to make a call, the automatically rising receiver hook closes the two branches of the line at the local station to complete a circuit for the line relays and thereby start the line switch into operation to make a call. Owing to the fact that the line relays are bridged across the ultimate talking circuit, to differences in lengths of lines, and to other circumstances connected with the construction and operation of automatic exchanges, these relays must be high-wound, and usually have a resistance of one thousand ohms or more. This makes those relays the most expensive part of the line switch construction. The main, or central object of the present improvement is to pro vide means by which one of these expensive line relays serves a plurality of line switches in initiating calls, and is then cut out of the connection so that it is notbridged across the ultimate talking circuit.

The means provided for accomplishing this result consists principally of a special or secondary apparatus which is associated with and serves from five to twenty line switches, the iuunber thus served by this special apparatus being determined in each case by the conditions of traflic to which the exchange is subjected. What is more than this apparatus, consists of someaelectrical connections to be hereinafter described.- As the present improvement does not go beyond the line switches, the draw ings and description do not extend beyond making connections to the first selectors and the electrical connections before mentioned.

As line relays are common to different forms of line switches, and as the present improvement relates principally to cutting out these relays, the actual construction of the line switch is not material. In the drawings, which are diagrammatic, I have shown a line switch of the drop type, similar in general character to what I have shown in my pending application Serial Number 108,265, :[iled July 10, 1916, and issued as Patent No. 1,264,826, on April 30, 1918. The restoration of the apparatus to normal position is of the pneumatic type similar to that illustra-ted' in my pending application Serial Number 186, I4S, filed August 16, 1917.

In the accompanying drawings Fig. 1 is a diagram showing two line switches and one secondary apparatus arranged to serve nine such line switches; and

Fig. 2 is a side elevation of one of the drops together with trunks to which it makes connection.

I In the said drawings, the first line switch is represented at A, the second at B, and the secondary or special apparatus at C. The lines 5 and 6 of both A and B are the two branches of the line leading from the subscribers station to his line switch, and across which branches the line relays are bridged in present constructions. These branches terminate in contact springs which are normally pressed upward against stationary contacts by a drop 7 normally held in the position shown in the drawings.

Each lineswitch has a cylinder 8 and piston O normally standing atthe lower end of the cylinder. The upper end of each cylinder is connected by a pipe 10 to a vacuum chest- (not shown), which connection is normally closed by a valve 11. When this valve is opened, the air in cylinder 8 over piston 9 is drawn out, and the piston rises to restore the apparatus as willbe hereinafter described.

In the special or secondary apparatus are a ratchet wheel 12 and disk 13 mounted upon a common shaft represented by dotted "is connected to the valve 18.

lines at 14. On this shaft, and insulated therefrom, are wipers 51 and 1-7 which are advanced step by step by the ratchet wheel to successive engagement with contact points as will be described later.

There is a. bar on'which are contact springs 16 arranged to normally close connections to the stationary contact points 15 Which are terminals of wires 25. The bar 15 is connected to a bellows 17,-w'hich is the same thing as the well known pneumatic used in player pianos. llhe pneumatic 17 is connected to a vacuum chest (not shown), which connection is normally closed by a valve 18. The disk 13 has a notch in it which is normally in engagement with the horizontal arm ofa bell crank lever 19 pivoted at 20. The other end of the bell-crank VVh'en the ratchet wheel '12 anddisk 13' are advanced, as Will be described, the movement of the disk'moves the bell-crank 19 to'open-the valve 18. When this occurs, the pneumatic 17f pulls the-bar 15 downward to break all connections made 'by the springs 16, and to establish a circuit as will be hereinafter described.

The other parts of the apparatus will be understood by a description of the operation.

It will be assumed that the subscriber whose line switch is represented at A, removes his receiver and consequently con nects lines 5 and 6 together at his local station. A circuit is then completed as follows: battery X2lrelay 2223 2425-fl265local station628-29 ground-X.

This attracts armature 30, whereupon another circuit is completed as follows: batmatrire to fall back and thus break the circuit for magnet 36. Advancing the ratchet wheel 12mov'es wiper 51 away "from spring 33, which brings about another break at 33-3 1 in the n'evijously described circuit for magnet 86.

Drawing down bar 1.5 moves contact sl' ringil to connection with contact point 12. This taken with the simultaneous falling back of armatures 30 and 38, closes a new circuit'iorma-gnet 36 as follows: X 21-3 0-8 94Q,41&2-13''143 8 8 37groundX.

When the circuit is so closed, magnet 36 'nected parts step by step as before.

advances ratchet wheel 12, and at the same times breaks its own circuit at #14:. Upon such break the armature 38 falls back to again make the circuit for magnet 36 and again advance ratchetwheel 12. By this means the ratchet Wheel'is automatically advanced step by step, carrying with it the parts connected to shaft 14.

In the path of Wiper'51 is a? series of contact point-s, difierent ones of which correspond to the different line switches served by the'apparatusC. Also, in the path of the wiper 1? is another series of contact points corresponding in the same way to the same line switches. The contact points in the path of wiper 51are connected to the startagain ing n'1agnots'53 of the different line switches,

and'those in the path of wiper a? are connected to thecontacts'26 ofthe different line switches.

hen the wiper at? reaches the contact point connected to-26 of the stationwhich has its relay 22 is completed as follows battery 'lsi 21-22-46wiper 4sT-4:825--26 '27-5 1oa1 station6- 28 29-ground 'lhus'closing the circuit for relay 22 causes its armature 3i) to break the circuit at 391 01 "magnet 36 and'thereby stop the apparatus C 'nect the subscribei"s line to contacts carried by the drop. In moving downward, spring 27 breaks the circuit at 26 for the relay 22, whereupon the armature 30 falls back and completes a circuit for magnet 86 as before. In this condition, the magnet 36 automatically advances the ratchet wheel 12 and con- If, in the mean time, some other local station in the group served by apparatus 0 has had its receiver remored, circuits will be completed thru wipers st? and 51 as before to energize magnet 53 of that stations line switch. Otherwise, the magnet 36 will continue to operate until the notch in disk 13 permits bell-crank lever 19 to return to normal position and thus close valve 18. lVhe-n this occurs the normal air leaks of pneumatic 17 will permit bar 15 to return to normal position. thereby breaking the circuit for magnet- 36 at contact 42. This stops the apparatus 0 until it is started again by some other subscriber in the manner described.

Each drop 7 has pivoted on its side an arm 55 adapted to engage any one of avseries of lit) pivoted bars M which happens to be in its path when the drop falls. l Vhen this occurs, the weight of the drop coming upon a bar M swings said bar on its pivot so that it is thereafter out of the path of a similar arm on another drop 7. The sameaction also moves arm 55 on its pivot to make an electrical connection to an insulated spring 56 connected to wire 52.

On the lower end of each drop 7 are wipers 59 and 64 which pass over contacts on trunks N when the drop falls. The trunks N correspond to the bars M so that when a drop 7 falls and is stopped by its arm 55 engaging a bar M in normal position, the wipers 59 and 64 will be in engagement with contact terminals on an idle trunk leading to an idle selector. hen this occurs a circuit will be completed as follows:-battery Y-relay 57158596O61286loca1 station5276263! -646566 relay 67ground-Y.

The relays 57 and 67 are the line relays of a selector switch, and the Wipers shown on the end of trunk wires 58 and are the wipers of the same selector. The description so far sets forth the operations involved in reaching a first selector. From this point on, the construction and operations are the same as those in the ordinary exchange.

To make it possible to restore the apparatus to normal position at the end of a conversation, there is a connecting wire 68 from each bar M to the back contact for armature 70 of relay 57. This makes connection from battery Y tothe magnet 53 thru connections 55-56. To make it certain that thiscircuit will not be completed at the time the trunk is being selected, the parts 55 and 56 are arranged so that there is a slight delay in completing contact at this point. This gives relay 57 time to break the connection at 69-70.

The valve 11 is connected to the upper end of a. centrally pivoted lever 71, on the lower end of which is pivoted an arm 72 having a projection 73 and a hook '74. \Vhen the parts are in normal position, a lug 75 on drop 7 engages the end of arm 72 and holdsthe projection 7 3 just above the upper end of armature 54. WVhen magnet 53 is operated to release drop 7, armature 54 passes under projection 73 without touching. lVhen drop 7 falls, lug 75 falls also and permits spring 76 to move arm 72 down against the end of armature 54. When the circuit is broken thru magnet the armature 54 passes to the left of projection so that another attraction of armature 54 will move lever 71 on its pivot to open valve 11, and also will cause hook 74 to engage and be held by a stationary hook 77. I

The circuit previously given thru relay to close valve 11.

57 is one which is held during talking. \Vhen, however, the subscriber hangs up his receiver he breaks the connection between his branches 5 and 6 with the result that armature 70 falls back. hen this occurs, a circuit is completed as follows :Y 706968-78555652--53- ground-Y.

This is the operation which opens the valve 11 and permits vacuum to raise the piston 9. On the piston 9 is a hooked l'OC 79 which engages a projection 80 on the drop 7 to raise said drop to its normal position. In rising, the circuit for magnet 53 is broken'by arm 55 leaving bar 78, but

catch 77 is at this time in engagement with catch 74 and holds the valve 11 open. A drop 7 reaches its normal position, lug 75 engages arm 72 to release hook 74 from hook 77. Spring 81 then moves lever 71 The vacuum connection being no longer on behind piston 9, said piston returns to the normal position shown in the drawings.

I have heretofore referred to the apparatus C as asecondary apparatus because it is an addition to other apparatus for eliminating expensive line relays. In a different sense it would be more appropriate to refer to apparatus C as a. primary apparatus because its. operation precedes the actual operation of the line switch in selecting a trunk. The terms primary" and secondary, are not here used in opposition to each other,'but rather as complementary to each other.

In the present arrangement, the wipers 59 and 64 do not begin their trunk hunting movement immediately upon the subscriber removing his receiver, but do so only after the wipers 47 and 51 of apparatus C have been moved two or more steps from normal position. Normally these operations will occur before the calling subscriber is ready to operate the dial of his calling device, but there are conditions in which there would be delays in apparatus 0 such that the subscriber would operate the dial before wipers 59 and 64 had found a trunk. Such a. condition could arise if three or four subscri-bers served by the same apparatus C should remove their receivers at substantially the same time. The wipers 47 and. 51 would pick these calls up in rotation, but would be delayed in reaching the last one. e

To meet these conditions I provide the device shown at D for deliverying a tone to the receiver during the interval from the time it is lifted from its hook to the time the drop 7 falls to connect to an idle trunk. This is accomplished by connecting condensers 82 between the lines 25 of the different line switches, and the grounded secondary 83 o't'an induction coil which has its priniarv arranged ina make-and break 'dev-ice operated by battery Z. As long as ing drop 7,'this tone 'willbe cut off by the breaking of the connection at 26.

Fi-oin the foregoing desci'ipt'on it will be seen that thereare no line relays bridged between the lines 5 and 6 leading to the line switches. Instead thei'eott there is one line relay 22 connected in multiplethru 23 and 26 to the lines 5 ot'a plurality of'local stations.

The relay 22, together with the other parts of apparatus C, serves all of the purposes er a large number of expensive relays in starting a plurality or line switches into operation.

What I claim is 1. In a telephone exchange, the'c'oinbination with lines leading from a plurality of local stations to acorresponding plurality of line switches at a central oflice, of a relay connected in multiple to said lines, and devices controlled by said relay for breaking the connection between said relay and said lines and for starting the line switches into operation.

2. The combination with lines leading from a plurality of local stations to a corresponding plurality of line switches at a central office, and a magnet at each line switch for starting such switch into operation, of a relay connected in multiple to said lines'and'controlled from the local stations, and devices controlled by the relay for closing an electric circuit for the magnet which corresponds to the local station which at the time controls the relay.

3. The combination with a plurality of lines leading from local stations to a central office, and a corresponding plurality of-starting magnets located at the central ofiice, of a pair of insulated wipers, means controlled from any local station for advancing said wipers to make connections to lines and corresponding magnets, and means by which the advancing wipers will close an electric circuit for the magnet which corresponds to the line controllii'ig the movement of the wipers.

at. The combination with a plurality of telephone lines leading from local stations to a oentraloifice, and a relay connected in multiple tosaid lines and controllable from any one of said local stations, oi means for breaking said multiple connection and substituting thereforsuccessive connections between the'relay and the lines.

'5. A plurality of lines leadingfrom local stations to a central office, a relay connected in multiple to said lines, means controlled by 1 season the relay for breaking the multiple connectionsand substituting therefor connections in rotation from the relay to" the lines, line switches associated with the lines, and means controlled from any station for starting the associated line switch into operation when the connections in rotation bring the relay into connection with the station.

6. The combination with a series of subscribers lines,- a corresponding series of line switches, and a starting magnet for each hne switch, of a pair 01" insulated wipers, movable simultaneously over corresponding "will close a circuit for the starting magnet of the corresponding line switch.

7. The combination with a-series ofsub- 'scribers lines, a corresponding series of trunk selecting devices, and a magnet associatedwith each trunk selecting device, of insulated wipers, contact points in the paths of the wipers, propelling mechanism for moving said wipers simultaneously over corresponding contact points, connections from one set of contact'points to the'lines and from the other set of contact points to the corresponding magnets, means controlled from the local station on any one oft-said lines for starting said propelling mechanism into operation, and means by which upon one of said wipers engaging the contact point connected to the line over which the propelling mechanism was controlled the other of said wipers will complete an electric circuit for the corresponding magnet.

8. A plurality of telephone lines, a relay connected in multiple to said lines, automatic means for breaking the multiple connections and substituting therefor connections in rotation'from the relay to the lines, and means operating through such'rotation forconnecting one of said telephone lines to a trunk line. I

9. The combination with a series of tele- 'phone lines, a series of trunk lines, and devices for connecting the telephone lines to the trunk lines, of a pair of insulated wipers, contactpoints in the path of each wiper, propelling means for moving the wipers to'success'ive engagement with their contact points, connections from one set of contact points 'tothe telephone lines and from the other set of contact points to the connecting devices, and means'by which upon onewiper engaging a pointconnected to a line which is closed at its local station the other wiper will close a circuit for a connecting device to connect such line to an idle trunk.

10. The combination with a series of telephone lines, a corresponding series of magnets, and trunk selecting devices controlled by said magnets, of devices for automatically closing electrical connections to the lines and corresponding magnets in succession, abattery and means bywhich upon said devices closing connection to a line which also is closed at its local station said battery will be operatively connected to the corresponding magnet.

11. In a telephone system, a group of lines, a selecting switch for each line, a line relay common to all of said switches and used by each switch in extending a call, said relay norn'ially connected to said lines, and means for disassociating said relay "from all the other switches of the group while a connection is being extended from one line and for restoring the relay for use with the other switches while the first connection is maintained.

12. In a telephone system, a group of lines, a line relay common to and normally connected to said lines and usable by any line when extending a connection, and means for preventing more than one line from using said relay at one time.

13. In a telephone system, a group of lines, a line relay common to and normally connected to said lines and usable by any line when extending a connection, means for preventing more than one line from using said relay at one time, and means for connecting a busy signal to any line which ini tiates a call while said relay is in use by another line.

14. In a telephone system, a plurality of lines, a selecting switch for each line, a line relay normally connected to all of said lines; a controlling device common to said lines controlled by said relay to connect said derice in rotation to the lines for use in extending connections therefrom, means for preventing the extension or" a connection from any other line while said device is in use by another line, and means for connecting a signal to any line which attempts to call while the device is being so used by another line. I

15. In a telephone system, a group of lines, an automatic switch for each line, a line relay common to said switches, a finder switch for connecting said relay to any one of said switches for controlling the operation thereof, said relay operating when a call is initiated from any line to start said finder switch, and operating again to stop the finder switch when the connection is made with the automatic switch associated with the line calling.

16. In a telephone system, a group of lines, a line relay common to and normally connected to said lines, means for operating said relay from any one of said lines to extend a connection therefrom, and means for disassociating said relay from all the other lines.

17. In a telephone system, a group of lines, a line relay common to and normally connected to said lines, a selecting switch individual to each line, means for operating said relay from any one of said lines for initiating the operation of the selecting switch individual to said one line, and means for disassociating saidrelay from all the other lines.

18. In a telephone system, a group of lines, a line relay common to and normally connected to said line, a selecting switch individual to each line, means for operating said relay from any one of said lines, means for disassociating said relay from all of said lines to cause said relay to deenergize, means for connecting said relay to said lines in succession and means for again energizing said relay when said one line is found whereby the switch individual to said one line is operated.

19. In a telephone system, a group of lines, a line relay normally connected to all of said lines, a selecting switch for each line normally disconnected therefrom, said relay operated from any line when calling to break its normal connection to all the other lines to find the switch associated with said line and connect it thereto.

20. In a telephone system, a plurality of lines, an automatic switch for each line, a line relay controlled from any of said lines to start the trunk selecting operation of the switch associated with that line, and pneumatically operated means controlled by said relay for disconnecting itself from all other lines while being controlled from any one line.

21. In a telephone system, a group of: lines, a relay connected by multiple connections to all the lines of said group and operated from any line to control the extension of a connection therefrom, a pneumatic device for breaking all of said multiple connections, and means controlled by the relay for withdrawing air from said device to cause its operation.

22. In a telephone system, a group of subscribers lines, automatic switches for extending connections from said lines, a line relay common to and normally connected to all said lines, a finder switch for connecting said relay to any one of said switches for controlling the operation thereof, said relay operating when a call is initiated from any line to start said finder switch, and operating again to stop the finder switch when a connection is made with one of said switches.

23. In a telephone system, a group of subscribers lines, automatic switches for ex? tending connections from said lines, ailine relay common to and normally connected to mesaeae operating whena call is initiated from any line to start said finder switch, and operating again to stop the finder switch when a connection is made with one ofsaid switches, and means for disassociating said relay from all the other lines.

FRANK A. LUNDQUIST. 

